As electronic components become smaller and more powerful, their heat dissipation requirements also rise dramatically. With high or low frequency printed circuit board (PCB) assemblies when an aluminum heat sink is attached to a printed circuit board, an interface must be used that ensures a proper electrical connection. The interface may also serve as a thermal connector.
Historically, electrically (and thermally) conductive interface materials are mainly based on thermoset polymers, such as epoxy resins. Once a thermoset polymer is cured, it is inflexible. Thus, a major drawback of interface materials based on thermoset polymers is their inability to expand or contract with changes in the surrounding temperature. Also, epoxy resins usually have a lower temperature stability (up to about 400 F) as compared to silicones that can be used up to about 550 F. As a result, high power PCBs based on thermoset interfaces can exhibit weakening or even delamination at the circuit/heat sink interface if the interface temperature exceeds about 400 F due to the high heat generated during the performance of high power electronic components that are assembled over the PCB. There is a need, therefore, for an advancement in the art of preparing electrically and thermally conductive interface materials and in manufacturing circuit board assemblies using the interface material.